The present invention relates to a data processing technique, and more particularly to a technique which is effective when applied to a database management system having a system switching function.
There is a need for a robust system operating 24 hours a day, every day in the world of Net business in which service interruption could lead to loss of a great business opportunity. What is important with such a system is to localize the influence of a failure when it has occurred and quickly restore the system. To quickly recover from failure, database (DB) systems conventionally use a system switching technique in which a standby system machine is installed in addition to a running system machine for performing service processing, beforehand, and when a failure has occurred in the running system machine, the standby system machine takes over the service processing.
For example, in literature published by Morgan Kaufmann Publishers in 1993, Jim Gray and Andreas Reuter disclose a hot standby noninterrupted system employing an HA (high availability) system configuration to provide resistance to DB failure. Jim Gray and Andreas Reuter, Morgan Kaufmann Publishers, 1993 “TRANSACTION PROCESSING: CONCEPTS AND TECHNIQUES”, pp. 646-648, pp. 925-927.
In the literature “Parallel Database Systems: The Future of High Performance Database Systems”, on the other hand, David DeWitt and Jim Gray disclose an architecture (technique) in which the processing load on a database is distributed to a plurality of processors for parallel processing (COMMNICATIONS OF THE ACM, Vol. 35, No. 6, 1992, pp. 85-98). In the “Shared everything, Shared disk” architecture employed by the above technique, each computer for executing DB processing can access all data, whereas in the “Shared nothing” architecture, each computer can access only the data stored in the disks connected to itself. Parallel Database Systems: The Future of High Performance Database Systems (David DeWitt and Jim Gray, COMMUNICATIONS OF THE ACM, Vol. 35, No. 6, 1992, pp. 85-98)
The “Shared nothing” architecture is advantageous over the “Shared everything, Shared disk” architecture in that it requires fewer resources to be shared between the components conducting the DB processing and thereby provides higher scalability. The “Shared nothing” architecture also employs a system switching technique in many cases to provide high availability.